Black Layer Stage Research Articles

Effects of several commercial or pure lactic acid bacteria inoculants on fermentation and mycotoxin levels in high-moisture corn silage

Effects of 3 commercial lactic acid bacteria (LAB) inoculants and 6 single strains of LAB on fermentation and levels of aflatoxins and other mycotoxins in high-moisture corn (HMC) silage were examined. Corn plants were inoculated with Aspergillus flavus at silk emergence and wet corn kernels were harvested at black layer stage (dry matter [DM]: 704 ± 5.0 g/kg). Samples were ground and ensiled directly (control group, CTR) or after treatment with one of the 9 LAB inoculants. The commercial inoculants contained Lentilactobacillus (Lent.) buchneri LB1819 and Lactococcus lactis O224 (SiloSolve FC; Chr. Hansen A/S, Hørsholm, Denmark), applied at a final dose of 250,000 CFU/g or 1,250,000 CFU/g (SiloSolve FC1x and SiloSolve FC5x, respectively); and Lent. buchneri and Lactiplantibacillus (Lac.) plantarum (Pioneer brand 11B91, Pioneer Hi-Bred International, Des Moines, USA) applied at a final dose of 250,000 CFU/g. One pure strain of Levilactobacillus (Lev.) brevis DSMZ 20054, two pure strains of Lac. plantarum (LP ATCC 8014 and LP PB) and three of Lacticaseibacillus (La.) rhamnosus (LR ATCC 7469, LR LR7 and LR RI) were also applied at a final expected dose of 250,000 CFU/g. Wet corn kernels were ensiled in 20 L mini-silos, compacted to a density of 389 kg DM/m3, and stored at room temperature. Conditions before ensiling were pH 5.87 ± 0.169, and (log10 CFU/g) of 7.68 ± 0.473 for LAB, 5.71 ± 0.121 for molds and 6.81 ± 0.341 for yeasts. The mini-silos were opened after 30 or 120 days. From day 30–120 days, levels of acetic acid, propionic acid and 1,2 propanediol increased (P < 0.05) in the SiloSolve FC1x, SiloSolveFC5x and Pioneer 11B91, and in LR LR7 groups. During this time, butyric acid level increased 5-fold in CTR; by two to three-fold in pure strains groups; and only slightly in the three commercial inoculants and the LR LR7 (P < 0.05). Aerobic stability increased (P < 0.05) with storage time from 32 to 97 h, and the commercial inoculants and LR LR7 groups had longer stability than CTR (P < 0.05). The storage time and the inoculants did not affect aflatoxin levels. No zearalenone or tenuazonic acid were detected in the mini-silos, even if they contaminated the corn plants. Results indicate that different silage inoculants affected fermentation of HMC and its contamination by mycotoxins, although no inoculant had an effect on levels of aflatoxins.

Perdas fermentativas e estabilidade aeróbia de silagens de milho inoculadas com bactérias ácido-láticas em diferentes estádios de maturidade

Objetivou-se, nesta pesquisa, avaliar o efeito de inoculantes bacterianos em silagens produzidas com plantas de milho em diferentes estádios de maturidade quanto às perdas fermentativas e estabilidade aeróbia. Utilizou-se o delineamento inteiramente casualizado, em esquema fatorial 3x5, e avaliaram-se dois inoculantes (Silobac® e Maize All®) e uma silagem controle em 5 estádios de maturação fisiológica do milho, com 4 repetições. Verificou-se efeito positivo dos inoculantes quanto às perdas fermentativas, e a adição de Silobac® e Maize All® promoveram perda de matéria seca (PMS) 1,78 e 1,75 pontos percentuais a menos que a silagem controle (7,95%). As silagens produzidas com 2/3 de linha de leite e camada negra (CN) apresentaram menor PMS, o que se deve principalmente a menor produção de efluente. A silagem que levou maior tempo para apresentar quebra da estabilidade aeróbia foi aquela produzida a partir de plantas de milho no estádio camada negra e inoculada com Maize All®, ao passo que se notou menor estabilidade para outras silagens inoculadas com esse mesmo produto em virtude do aumento no teor de umidade das silagens. Os inoculantes utilizados neste trabalho são eficientes em diminuir as perdas de MS durante o processo fermentativo, contudo, contribuem com maior aporte de nutrientes nas silagens, o que resulta em menor estabilidade após a abertura dos silos. Silagens produzidas com maior concentração de MS apresentam menores perdas de MS durante a fermentação, assim como são mais estáveis em contato com o oxigênio.

Ruminal degradability of hard or soft texture corn grain at three maturity stages

The predominance of vitreous endosperm in hard texture flint corn (Zea mays L.) can decrease ruminal starch digestion comparatively to the farinaceous endosperm of dent corn, reducing energy content of the grain. The objective of this experiment was to evaluate the effects of texture and maturity stage on ruminal degradability of corn grain. Two dent and two flint hybrids were harvested at the early dent, half milk line, and black layer stages. The proportion of vitreous endosperm (vitreousness) in dent hybrids was 44.3%, while in flint it was 67.0%. There was a linear increase in vitreousness with advancing maturity. Flint hybrids at the early dent stage were more vitreous than dent at the black layer stage. The increase in vitreousness per maturation day was greater for flint hybrids. Grains were incubated in situ in the rumen of 6 cows. The 24-hour ruminal dry matter degradation was 63.3% for dent corn and 52.4% for flint corn. The 72-hour incubation residues of dent and flint hybrids were 7.6% and 15.6%, respectively. Ruminal degradability was similar between hybrids at the early dent and half milk line stages. There was a marked texture effect on ruminal degradability at the black layer stage (quadratic effect of maturity stage and interaction between texture and maturity stage). Use of dent hybrids, compared to flint hybrids, may result in smaller relative reduction in ruminal starch digestion in situations of late grain harvesting.

Performance of Holstein cows fed sugarcane or corn silages of different grain textures

Corn cultivated in Brazil is predominantly of hard texture, and more propense to decreased starch digestibility under late harvesting situations than dent hybrids. This work tested the utilization of dent corn as a way of extending the ensilage period without reducing animal performance, and evaluated the potential of sugarcane as a forage for high-producing dairy cows. Nine lactating Holstein cows were allocated to three 3 ' 3 latin squares and were fed 200 g of forage neutral detergent fiber per kg of dry matter as either hard texture corn ensiled at the half milk line stage of maturity, soft texture corn ensiled at the black layer stage, or sugarcane. There were no detectable differences between corn hybrids with regard to milk yield (34.2 vs 34.6 kg d-1) and composition, dry matter intake (23.0 vs 23.2 kg d-1) and total tract apparent digestibility of nutrients. Sugarcane decreased feed intake (21.5 kg d-1) and milk yield (31.9 kg d-1). Organic matter digestibility, chewing activity and rumen pH did not differ among treatments. Sugarcane seems to be a viable option to feed groups of Holstein cows during lactation stages in which nutrient demand is not at a maximum. The performance of dairy cows fed dent corn ensiled at the black layer stage of maturity was similar to the performance of cows fed flint corn ensiled at the half milk line stage.

Relationship Between Corn Vitreousness and Ruminal In Situ Starch Degradability

The objective of this experiment was to determine the relationship between corn kernel vitreousness and ruminal in situ starch degradation. Fourteen U.S. and five Brazilian corn hybrids cultivated in their respective countries were evaluated. The U.S. dent hybrids were harvested at one-half milk line, black layer, and 21 d after black layer stages of maturity. Brazilian flint hybrids were harvested only at the latest stage of maturity. Vitreousness was determined by manual dissection of the kernels. Ruminal in situ degradation of starch was determined in three lactating Holstein cows fitted with ruminal cannulae. Vitreousness of the five mature Brazilian hybrids averaged 73.1% (range of 64.2% to 80.0%), while vitreousness of the 14 mature U.S. hybrids averaged 48.2% (range of 34.9% to 62.3%). Within the 14 U.S. hybrids, average vitreousness increased from 42.8% to 48.2% as stage of maturity progressed from one-half milk line to 21 d after black layer. The correlation between kernel density and vitreousness was 0.87. The correlations between kernel vitreousness or density and ruminal starch availability were −0.93 and −0.87, respectively. With advancing maturity, kernel vitreousness and density increased while ruminal starch availability decreased. Kernel vitreousness and density may be useful parameters for which to select corn hybrids for high ruminal starch availability. Density may be a more practical measurement than vitreousness for screening large corn data sets.

Effects of processing whole-plant corn silage on growth performance and nutrient digestibility in feedlot cattle (1998)

Sixty crossbred heifers and 12 crossbred steers were used to evaluate the effects of mechanically processing (crushing the kernels of) whole-plant corn silage on feedlot perforTrial 1. Sixty mixed breed, crossbred mance and nutrient digestibility. The three heifers (avg wt, 591 lb) were used in a comtreatments were: preensiled processed, pletely randomized designed, 80-day growth postensiled processed, and nonprocessed trial. Three whole-plant corn silage treatcorn silages. Heifers fed the processed corn ments were compared: preensiled processed silages grew faster and were more efficient (PRE), postensiled processed (POST), and than those fed nonprocessed silage. Steers nonprocessed (control). The heifers were consuming the two processed silage rations allocated randomly to one of 15 pens (four had numerically higher DM, OM, NDF, and head per pen), and the treatments were asADF digestibilities and significantly higher signed randomly to blocks of three pens. Dry starch digestibilities than those fed the nonmatter intake, ADG, and feed efficiency were processed silage ration. These data suggest measured. The heifers were weighed individthat processing whole-plant corn silage ually on 2 consecutive days (February 19 and before or after ensiling has a positive effect 20, 1997), and the average was used as the on both rate and efficiency of gain and nutriinitial weight. Final weights were obtained in ent utilization, particularly when the kernels the same manner on May 9 and 10, 1997. approach the black layer stage of maturity. Each ration contained 90% of the appropriate

Impact of the Maturity of Corn for Use as Silage in the Diets of Dairy Cows on Intake, Digestion, and Milk Production

Whole-plant corn was harvested at early dent, quarter milkline, two-thirds milkline, and black layer stages to evaluate the effects of maturity on intake, digestion, and milk production when corn was fed as silage in the diet. Twenty multiparous Holstein cows were used in a replicated experiment with a 4×4 Latin square design with 28-d periods. Diets containing 50% forage (67% corn silage and 33% alfalfa silage) and 50% concentrate (dry matter basis) were fed as total mixed rations. Moisture contents were 69.9, 67.6, 64.9, and 58.0% for silages from corn harvested at early dent, quarter milkline, two-thirds milkline, and black layer stages, respectively. Intakes of dry matter were similar across the four treatments and ranged from 3.73 to 3.79% of body weight. Milk production was highest (33.4 kg/d) for cows fed silage from corn harvested at the two-thirds milkline stage and lowest (32.4 kg/d) for cows fed silage from corn harvested at the early dent stage. Milk protein production was highest for cows fed silage from corn harvested at the two-thirds milkline stage (1.17 vs. 1.12 to 1.13 kg/d). Apparent total tract digestion of dry matter, organic matter, crude protein, acid detergent fiber, and starch was lowest for cows fed silage from corn harvested at the black layer stage. Although starch intake was similar for cows fed silage from corn harvested at the two-thirds milkline stage and for cows fed silage from corn harvested at the black layer stage (9 kg/d), intake of digestible starch was 0.4 kg/d lower for cows fed silage from corn harvested at the black layer stage. The optimum stage for corn that was ensiled was two-thirds milkline with some flexibility between quarter and two-thirds milkline.

Effects of an Enzyme Additive on Composition of Corn Silage Ensiled at Various Stages of Maturity

Corn forage at the milk, soft dough, and black layer stages of maturity (22, 28, and 44% DM, respectively) was treated with an enzyme additive at 1, 10, or 100 times the recommended dose and ensiled in laboratory silos at 26°C. By in vitro assay, the additive contained a full complement of cellulase and hemicellulase activities. The pH and temperature optima for cellulase and hemicellulase activities were 4.8 and 50°C, respectively. Regardless of dose, the additive had no effect on fermentation acids or nitrogenous compounds in silage at any maturity; however, high doses increased the glucose content of silage at the milk stage of maturity and increased ethanol content at the soft dough stage. Across maturities, addition of the enzyme additive resulted in a linear decrease in ADF, NDF, and hemicellulose content of corn silage but decreased the acid detergent lignin content of silage only at the milk and black layer stages of maturity. The enzyme additive had no consistent effect on in vitro NDF digestion.

Effect of Seed Maturation and Genotype on Seed Vigor in Maize

High quality seed is the goal of all corn (Zea mays L.) seed producers. The objective of this investigation was to relate several indicators of seed maturity [black layer (BL), milk line (ML)], to seed vigor (cold test and conductivity) over a wide range of dent corn genotypes and environments. Two inbreds (B73, Mo17), four single and modified single cross hybrids, and seven open pollinated, double and three way cross hybrids were produced at two locations (Lexington and Danville, KY) from 1985 to 1989. In 1986 and 1987, a complete plant defoliation treatment was also imposed on inbred, single and double cross hybrids. Seed harvests were started at approximately 30 d after pollination and continued at short intervals (≈4 d). Seed vigor reached maximum levels at physiological maturity (PM) which occurred at black layer Stage 4 for single and double cross progeny. Maximum seed vigor occurred slightly later for inbreds between black layer Stages 4 and 5. There was a significant quadratic relationship between seed vigor (cold test and conductivity) and black layer maturity across all years in each genotype grouping including stay‐green hybrids. When plants were stressed by defoliation or high temperatures during seed development, the seed weight was reduced, seed maturation was accelerated, but maximum seed vigor occurred at the same stage (BL4) as for nonstressed plants. Maximum seed vigor levels consistently occurred at physiological maturity as determined by black layer (or milk line), which can be used by seed producers to estimate the date of harvest.

Hybrid Quality and Yield Differences for Corn Silage in Pennsylvania

Differences among corn (Zea mays L.) hybrids for forage quality traits have been reported, but the stability of forage quality differences over diverse environments is not well documented. To evaluate hybrid stability for yield and forage quality, nine commercial hybrids were evaluated at two locations in Pennsylvania in 1990 and one location in 1991. All hybrids were harvested on the same day at the 2/3 milk line to black layer stage, depending on the hybrid. Whole plant and stover sub-samples were collected from each plot, chopped, dried, and ground for analysis. Forage analysis for crude protein (CP), acid detergent fiber (ADF), neutral detergent fiber (NDF), and in vitro dry matter disappearance (IVDMD) was performed using near infrared reflectance spectroscopy (NIRS) on both whole plant and stover samples [...]

Corn Seed Maturity Indicators and their Relationship to Uptake of Carbon‐14 Assimilate

Various maturity rating systems have been proposed to evaluate seed development in corn (Zea mays L.). The objective of this research was to determine the relationship of seed assimilate uptake and dry weigh to three indicators of physiological maturity: moisture concentration, black layer, and milk line development. Assimilate movement into the seed was determined by exposing the leaf subtending the ear to 14CO2 at regular intervals during seed development and measuring the 14C 24 h later in F2 seed of B73 ✕ Mo17 (1984, 1985) and the stay‐green hybrids FS854 and Pioneer Brand 3358 (1985). In 1986 and 1987, plants of the same F2 hybrids and the inbreds B73 and Mo17 and their F1 cross (B73 ✕ Mo17) were defoliated at ≈20 d after pollination and seed development was compared to that of undefoliated plants. Seed dry weight, moisture concentration, and milk line and black layer development (using a five‐stage rating system) were determined at 3‐ to 5‐d intervals. Uptake of 14C‐assimilate by seed and cob tissue decreased sharply near the end of the linear phase of seed dry weight accumulation when the milk line and black layer ratings were at Stage 3 (mid‐milk line) greater. Near Stage 4 of both black layer and milk line development, 14C in the seed had fallen to the lowest levels, maximum seed weight had been reached, and the seed were physiologically mature. Both black layer and milk line followed consistent rends throughout seed development for all hybrids (including the stay‐green genotypes), defoliation treatments, and years. Seed moisture during seed development was highly correlated with both black layer and milk line, but the concentration at black layer Stage 4 was more variable (293–415 g kg−1) across genotypes and years. The data suggest that Stage 4 of both black layer and milk line development represents a useful and reliable indicator of physiological maturity.